Field of the Invention
The invention lies in the field of circuit technology. The invention concerns an integrated circuit including a functional device that can occupy a first and a second operating state, and a control device for switching between the states.
Clocked operating semiconductor memories, so-called SDPAMs, have a standby mode and an active mode, as described in Siemens Data Sheet "HYB39S64400/800/160AT(L), 64Mbit Synchronous DRAM", Issue 7.98, Pages 7 to 13, in particular Page 8. The chip is in standby mode when the supply voltage is applied. The mode register is configured through input of a sequence of control signals and the active mode is set. The commands "Mode Register Set", "Precharge All", "Auto/Self Refresh", and "Row Activate" must be input in that order. Including the supply voltage, eight terminal pins must be supplied with potential or signals: VDD, VSS, CKE, CS, CLK, RAS, CAS and WE.
During operation in the system, the signals are fed from a microcontroller over the chip housing terminals. In order to test functional features in the active mode during a semiconductor chip test, the test device must be capable of applying the above signals in the required sequence. Particularly, test equipment for visually inspecting a semiconductor slice at the end of manufacture and before being cut into the individual chips, often lacks appropriate devices for feeding such signals. Separately, eight needles must be set on the chip in order to feed in the signals. Chip area is hidden and visual inspection is restricted because semiconductor memory connection areas for input signals are not located near the edge of the chip but in its middle. As a result, manual positioning of the probe needles requires a considerable outlay of work and expense.